This invention relates to a wear-proof paint for polymers such as rubber and plastic which are adapted to be used door glass-run of automobiles.
A known wear-proof paint has a base composition including a urethane prepolymer A, urethane prepolymer B, silicon oxide and carbon. The urethane prepolymer A is obtained by the reaction of a polyester resin having hydroxy groups in its terminal and a molecular weight of 1,000 to 3,000, synthesized from a saturated diol having 3 to 8 carbon atoms, an organic dicarboxylic acid having 4 to 10 carbon atoms (or an organic dicarboxylic acid anhydride) and a triol having 3 to 8 carbon atoms with an organic diisocyanate in the molar ratio of NCO/OH of from 1/1.1 to 1/1.4. The urethane prepolymer A has hydroxy groups in its terminal and molecular weights of 4,000 to 9,000. The urethane prepolymer B is obtained by the reaction of a triol having 3 to 8 carbon atoms with an organic diisocyanate having 6 to 14 carbon atoms in the molar ratio of NCO/OH of 2/1. The urethane prepolymer B has isocyanate groups in its terminal or trimer of organic diisocyanate.
In order to give wear-proof function, ingrediants such as inorganic particles, organic particles and/or oil are added to the base composition. These ingrediants include fluororesin, silicone resin, glass beads, polyethylene, graphite, molybdenum disulfide and polyguanamin resin.
The known wear-proof paint proves to give good wear-proof characteristics under low friction, low loads (less than 1 kg/20 mm.sup.2) condition. The paint, however, cannot satisfy wear-proof characteristics under high loads condition.